Superior Catalytic Performance of Atomically Dispersed Palladium on Graphene in CO Oxidation

Though substantial advances have been made for a few reactions of industrial significance over single atom catalysts (SACs), the origin of the superior catalytic performance, the nature of the active sites and the reaction pathways are still the subject of debate. Even for CO oxidation over SACs on non-reducible substrates, the understanding is still limited. We investigated the performance of Pd atoms mono-dispersed on graphene (PdGr) for CO oxidation. Combing first-principles-based thermodynamics calculations and microkinetics modeling, we showed that the positively charged PdGr can exhibit a rather high low-temperature activity for the CO oxidation. Under reaction condition, Pd atom binds strongly with O2, acting as the reactive species to convert CO. A comparison of the conversion rates of steps along different potential reaction pathways provides direct evidence that CO oxidation mainly proceeds through a revised Langmuir–Hinshelwood pathways and the dissociation of the peroxide intermediate (O-O-C=O...